1. Field of the Invention
The present invention relates to a transparent conductor.
2. Related Background Art
Transparent electrodes are used in LCDs, PDPs, organic ELs, touch panels and the like, and transparent conductors are employed as such transparent electrodes. A transparent conductor is formed from a base and a conductive layer, and some transparent conductors are obtained by film formation of a sputtering film (conductive layer) on the base, or by forming a conductive layer made of conductive particles and a binder on the base. However, when such transparent conductors are employed in high-humidity environments or in the presence of chemical substances such as organic solvents or organic gases (hereinafter also referred to as “high-humidity environments”), they gradually absorb moisture and chemical substances leading to increased electrical resistance of the transparent conductors themselves, and the variation in electrical resistance also tends to increase with time.
Thus, when such transparent conductors are used in a touch panel, for example, and left to stand in such an environment, the operability of the touch panel tends to become unstable.
A demand therefore exists for transparent conductors whose electrical resistance does not increase or vary with time as a result of absorption of moisture or chemical substances. Examples of resins for anchorage of conductive particles have been proposed, such as light-transparent conductive materials employing phenoxy resins or phenoxy/epoxy mixed resins, or polyvinylidene fluoride, which are considered to have low hygroscopicity (for example, see Japanese Unexamined Patent Publication HEI No. 8-78164 and Japanese Unexamined Patent Publication HEI No. 11-273874).
Since the aforementioned transparent conductors are formed by lamination of a base and conductive layer, warping or bending of the base produces bends in the conductive layer as well, and the conductive layer which is less flexible than the base becomes prone to cracking. Such transparent conductors are problematic because they generally exhibit increased electrical resistance.
Particularly when such a transparent conductor is used in a touch panel, the transparent conductor is subjected to a greater frequency of distortion because of the pressure normally applied to it. In such cases, the potential for cracking in the conductive layer of the transparent conductor is increased. If the conductive layer is formed as a sputtering film, the possibility of cracking is even greater since the conductive layer lacks flexibility.
It is therefore desirable to provide a transparent conductor in which such cracking is prevented without impairing the conductivity and transparency of the transparent conductor. For example, a transparent conductive laminated body has been proposed which comprises a transparent pressure-sensitive adhesive layer between the film base and the conductive layer (for example, see Japanese Patent Publication No. 2667680).